Apparatus for false twisting yarn

ABSTRACT

A false twist device having a plurality of guides on a guide plate rotatable about an axis and said guide plate being mounted in bearings which have a radius larger than the guide plate.

United States Patent McIntosh 1 Feb. 29, 1972 [54] APPARATUS FOR FALSETWISTING 58 Field of Search "57/34, 34 HS, 51,515, 77.3, YARN I57/77.33-77.45, 12

[72] Inventor: Bruce Murray McIntosh, Harrogate, En- [56] ReferencesCited gland 73 Assignee: imperial Chemical Industries Limited, UNITEDSTATES PATENTS London, land 3,355,872 12/1967 Gilchrist et al......57/34 us 22 Filed; 1 1970 3,408,807 1 H1968 Sylthe ..57/l2 X 3,412,54311/1968 Horvath ..57/34 HS [21] Appl. No.: 64,763

' Primary Examiner-Donald E. Watkins Related Apphcauon DamAttorney-Cushman, Darby & Cushman [62] Division of Ser. No. 757,077,Sept. 3, 1968, Pat. No.

3,553,952. [57] ABSTRACT [30] Foreign Application Priority Data A falsetwist device having a plurality of guides on a guide plate rotatableabout an axis and said guide plate being Sept. 4, Great Bl'ltalflmounted in bearings which have a radius larger than the guide late. [52]US. Cl ..57/77.45,57/77.33 p [51 Int. Cl. ..D02g l/02, DOlh 7/92 5Claims, 6 Drawing Figures Patented Feb. 29, 1972 2 Sheets-Sheet 2 2OFIGS APPARATUS FOR FALSE TWISTING YARN This is a division of applicationSer. No. 757,077; filed Sept. 3, 1968, now US. Pat. No. 3,553,952.

This invention relates to a process and an apparatus for making twistcrimped filaments. 7

It is known to make twist crimped filament yarn by imparting a falsetwist to a running multifilament yarn threadline by rotating it in afalse twisting device, and heat setting the twisted filaments so thatwhen they pass out of the twisted zone they remain crimped. For economicreasons high linear threadline speeds are preferred but these requirehigh false twisting rotational speeds to insert the desired number ofcrimps per inch into the resultant filaments. It is known to operatesuch afalse twist crimping process while drawing melt spun filamentyarn, but the high false twist rotational speeds required place arelatively low practical limit on the linear drawing speed. I

It is also known to make twist crimped filament yarns by processes inwhich there are no moving parts contacting the running threadline. Insuch methods two yarns are pretwisted around each other along part oftheir length and the yarns are then runas continuous threadlines throughsuch pretwisted zone with twist darnming means which completelypreventthe predetermined dammed twist from bleeding along the runningthreadlines. In known processes using this method no high twisting speedis needed but it has been necessary to introduce means such as conicalrollers to balance the tensions in the two'darn'twisted threadlines.Another disadvantage is that the filaments are less tightly crimped whentwo multifilament yarns are twisted around each other to a given numberof turns per inch then when single filaments are similarly twistedaround each other within one yarn.

We have now found that under certain conditions similar filamentarystrands can be continuously twist crimped by a dammed twist process evenat high speeds without theneed for any mechanism to balance the tensionsbetween such twisted strands so'that the strands may conveniently besingle filaments as well as multifilament yarns, and a multiplicity offine strands may readily be darn twisted together.

According to this invention we provide a dammed twist process for makingtwist crimped filament yarns comprising leading at equal speeds througha feeding device a plurality of filamentary strands which are nottwisted around each other and each of which comprises at least onefilament, and withdrawing such'strands at equal speeds under at'l'eastsome tension'through a forwarding device, between which feeding andforwarding devices strands are pretwisted around each other by 'a fixednumber of turns by mutual rotation between assemblies of guides, each'individual guide in such assemblies guiding one strand, and eachassembly having anaxis of symmetry coincident with the axis of thetwisted strands, such twist being heat set by heating and cooling suchtwisted strands between such assemblies of guides.

We prefer a process in which the angles of each individual strandthrough each individual guide in an assembly are equal.

We further prefer to use two mutually rotatableassemblies of guidescontacting eachmutually twisted group of strands.

The dammed twist crimping process of this invention. may be integratedwith drawing, in which case the forwarding device referredto'hereinbefore is a draw roll. By drawing we mean the operation wellknown in the art of converting melt spun filaments into useful textilefilaments by stretching them continuously to a ratio commensurate withtheir natural draw ratio. In such a process any known suitable drawingmeans m'aybe used, for instance heated feed-rolls, heated or unheatedsnubbing means or heating means which do not involve snubbing action. Wepreferthat atleast part of the filament stretch involved insuch drawingprocess takes place'before the filaments reach the twisted'zone. Whenthe chosen drawing means includes a heated zone in an essentiallystraight length of threadline path after at least the firstpartof thedraw, such heatedzone may conveniently be used for fulfilling also thefunction of heat setting the dammedztwist.

' be provided in parallel bundles from one bobbin which is side unwoundso that no unwinding twist arises. Multifilament strands may be over-endunwound each from a separate bobbin, the slight unwinding twist of thefilaments within the strands not significantly affecting the process ofthis invention provided that the strands are not twisted about eachother before'reaching the twisted zone between the feed and forwardingrolls.

According to another aspect of this invention we provide apparatus formaking twist crimped filament yarns comprising, between feeding andforwarding means, assemblies of guides having a common axis of symmetryand mutually rotatable about an axis parallel to such axis symmetry,means to cause and to prevent such mutual rotation, and between suchassemblies heating and cooling means to set twist.

We prefer such assemblies to be in planes at right angles to such axesof symmetry and rotation.

We prefer the axes of symmetry and rotation to be coincident.

In one preferred form such apparatus is mounted on a known drawingmachine such'that the feeding means of the apparatusof this inventionare the draw rolls of the drawing machine.

In another preferred form such apparatus is mounted on a drawing machine.fitted with known means for drawing filamentary strands such that thefeeding and forwarding means of theapparatus of this invention are thefeed and draw rolls respectively of the draw frame, and known drawingmeans are provided before the first guide assembly.

It will be ,clear that any known drawing means such as heating orsnubbing devices may be used.

FIG; I isa schematic perspective view of an apparatus embodying theprinciples of the present invention;

FIG. 2 is a elevational view of an orbital twister guide;

FIG. 3 is a sectional view taken on the line A-A of FIG. 2;

FIG. 4 is an elevational view of another form of an orbital twisterguide;

FIG. 5 is a sectional view taken on the line XX of FIG. 4;

and

FIG. 6 is a schematic elevational view illustrating use of the orbitaltwister guide as a double guide.

One embodiment of the apparatus of this invention is illustrated in FIG.I of the accompanying drawings in which two multihole twist stop guides31 and 32, the second of which may be rotated and clamped, are placedateach end of a zone 33 in twhich'are a heated plate 34and an unheatedspace 35. The guides 31 and 32 are vplaced between a feed roll 36 and adraw .roll 37 there being also a heated snubbing pin 38betweenthefeedroll 36 and theguide 31. In operation the strands 39-arepassed through corresponding holes in guides 31. andi32 andthenpassed-roundthefeed roll 36, round the snubbing pin 38-and roundthe drawroll 37. The guide 32 is then rotated through a predetermined number ofturns and clamped. The strands are thereby-twisted together betweenguides 31 and 32 as illustrated, the twisted filaments being heated bycontact-with the plate 34.

In this apparatus the filaments are drawn by a conventional snubbing pinand plate tandem hotdrawing process and theyaresimultaneouslyxtwistcrimpedaccording to the process ofthisainventionewhile passing overthe plate and through the cooling zonebetween the guides 31 and 32.

It will be appreciated that the guides 31 and 32 illustrated in FIG. 1of the accompanying drawings are not very convenient in practicaloperation because of the necessity to string up the strands by passingtheir ends through holes in the guides before such strands are drawn ina continuous process between feed and draw rolls. It is most desirableto use threadable guides into which continuous strands can be insertedwhile being forwarded continuously.

According to a further aspect of this invention we therefore provide animproved multiple threadline guide particularly suitable for the dammedtwist process of this invention comprising an assembly of threadableguides for individual strands symmetrically disposed about an axis ofsymmetry, rotatably mounted in bearings having a radius greater than theradius of a circle encompassing all such individual guides and suchassembly being provided with means to cause and prevent such rotation.Such a multiple threadline guide is referred to hereinafter as anorbital twister guide. Preferably such individual guides are in a planeperpendicular to the axis of rotation and concentrically and equallyspaced around such axis.

In a preferred form the orbital twister guide of this inventioncomprises a member rotatably mounted within bearings, in which memberinwardly directed slots in a plane at right angles to the axis ofrotation have inner closed ends symmetrically spaced about the axis ofrotation within a radius smaller than the radius of such bearings, andouter open ends which are separately threadable through slots in thebearings at angular positions of such member in such bearings at whichsuch slots in the member are inward extensions of such slots in suchbearings.

In another preferred form the orbital twister guide of this inventioncomprises a member substantially as described hereinbefore, rotatablymounted in bearings, one part of which may be removed to permit removaland reinsertion of the disc and then reassembled.

One embodiment of the orbital twister guide of this invention isillustrated in FIGS. 2 and 3 of the accompanying drawings. Two plates Iand 2 connected by spacing members 3 and 4 are pierced by circular holes5, each concentrically surrounded by recesses 6. The plates 1 and 2 arealso pierced by slots 7 which penetrate through the recesses 6 to theholes 5. In the recesses 6 are nylon bearing inserts 8 split so as notto close slots 7. A gearwheel 9 is fixed between concentric annularprojections 10, extending into the recesses 6 and seating in the nylonbearings 8. The gear 9 meshes with a pinion ll rotatably mounted betweenthe plates 1 and 2, on an axle 12 extending through the plate 1 andattached to driving and clamping means not shown. The subassembly ofgearwheel 9 and projections 10 is pierced by radial slots 13 eachcontaining an inserted ceramic threadline guide 14, such guides 14 beingarranged concentrically in the gear 9 on a circle with a diametersmaller than that of the holes 5.

In operation the gear 9 is rotated until a slot 13 is aligned with slots7 and a filamentary strand is inserted through such slots into a ceramicthreadline guide 13. The gear is then rotated until another slot 13 isaligned with slots 7 and a second strand is similarly inserted. Thisprocedure is repeated until all the strands required in a particularprocess are inserted each through a separate threadline guide 13. Thegear 9 is then rapidly rotated by driving axle 12 by means not shownuntil a desired number of turns of twist has been imparted to thestrands and then further rotation is prevented by clamping axle 12 bymeans not shown. During this twisting operation the strands are twistedbetween a twist stop and the orbital guide which when clamped acts asthe second twist stop. We prefer to use for the first twist stop eitheranother similar orbital twister guide or a slotted guiding membersimilar to that in the orbital twister guide but not rotatably mounted.

Another embodiment of the orbital twister guide is illustrated in FIGS.4 and of the accompanying drawings. A subassembly of gearwheel 20 andprojections 21 similar to members 9 and of FIG. 2 is provided withguides 22 similar to the guides 13 of FIG. 2 but spaced so as tocorrespond conveniently with the spacing of spinneret holes throughwhich the filaments to be crimped are extruded. Two pairs of housingplates 23 and 24 and 25 and 26 are connected respectively by spacingmembers 27 and 28 and are clamped together by means not shown along theline XX.

In operation the housing subassembly 23, 24 and 27 is removed, the guidesubassembly 20 and 21 is extracted, and held under a spinneret fromwhich emerge the filaments to be treated by the process of thisinvention. One monofilament or multifilament strand is passed througheach guide slot, the guide subassembly is reinserted in the housingplates 25 and 26 and the housing plates 23 and 24 are replaced andclamped along line X-X. A twist stop guide which may be a similarorbital twister guide is strung up similarly. The guides are positionedat each end of a heating zone provided between feed and draw rolls andthe strands are then strung up over such feed and draw rolls. Finallythe orbital twister guide is rotated to provide the required twist inthe running threadline.

The orbital twister guide of this invention is conveniently providedalso as a double guide as shown schematically in FIG. 6 of theaccompanying drawings. Two twisted threadlines are run in parallelthrough such a guide which provides S twist in the right-hand threadlineand Z twist in the left-hand threadline when rotated as shown, so thatthe threadlines may conveniently be plied after twist crimping toprovide a torque free crimped filament yarn.

The following examples illustrate our invention:

EXAMPLE I A melt spun twistless yarn of polyethylene terephthalateconsisting of 15 filaments each of 18 denier and having an intrinsicviscosity measured in orthochlorophenol at 20 C. of 0.65 and abirefringence of 0.008 was side unwound from a bobbin and the filamentswere threaded individually through a set of 15 concentric equally spacedholes each 0.03 inch diameter on a circle of 0.75 inch diameter in asteel disc of l inch diameter. The filaments were similarly threadedthrough three other similar discs which were then mounted in clamps, thefirst between the bobbin and the feed roll of a drawframe, the secondbetween a heated snubbing pin and a heated plate placed between the feedroll and draw roll of the drawframe, the third after the plate and thefourth before the draw roll. The discs were disposed so that theseparately guided filaments passed from the first to the fourth discwithout twist. The snubbing pin had a diameter of 2 inches and washeated to 95 C., the plate was 8 inches long and heated to 200 C. andthe third disc was placed 4 inches from the end of the plate. The yarnwas passed round the feed roll rotating at a surface speed of 25 r.p.m.,round the snubbing pin and over the draw roll which was rotated at 100r.p.m. The third disc was then rotated and reclamped when a twist levelof 70 turns per inch had been built up between the second and thirddiscs and the heated plate was brought into contact with this damtwisted part of the threadline. A drawn and bulked torque yarn withhighly crimped filaments was produced.

EXAMPLE 2 Two spun yarns of polyhexamethylene adipamide each containingtwo 35-denier filaments with a birefringence of 0.005 and a relativeviscosity of 35 measured at 8.4 percent concentration in percent formicacid at 25 C. were side unwound from bobbins and drawn to a ratio of 5.5at 1,000 ft. per minute on a draw frame comprising feed rolls heated toC., a 12 inches long plate heated to 230 C. and cold draw rolls. Twodouble orbital twister guides as illustrated in FIG. 6 of theaccompanying drawings were placed one between the hot feed roll and thehot plate and the other between the hot plate and the draw roll. A 6inch gap was left between the hot plate and the second orbital twisterguide, in which gap a draught of cooling air was directed on to thethreadline. The two filaments of each yarn were each slotted into twodiametrically opposed guides in one of the rotors of each double orbitaltwister guide. The second guide was then rotated at 1,100

rpm. until 120 turns per inch of twist had been built up in thethreadlines over the heated plate, being S twist in one threadline and Ztwist in the other. The orbital twister guide was then held stationaryand the two threadlines were plied at the draw roll and wound up to givea highly crimped balanced torque yarn.

EXAMPLE 3 Two 79-denier monofilaments of polyhexamethylene adipamidewith a birefringence of 0.0009 and a relative viscosity of 35 measuredas in Example 2 were over-end unwound from bobbins and processed asdescribed in Example 2 but using single orbital twister guides asillustrated in FIGS. 2 and 3 of the accompanying drawings and usingvarious draw ratios between 3.0 and 6.0. Using a tension motor in thecooling zone of the twisted threadline it was found that the maximumnumber of twists per inch that could be inserted without breaking therunning threadline was achieved at an optimum tension in the twistedregion of between 1.5 and 2 gm. per denier, corresponding to draw ratiosbetween 4.6 and 5.4, within which range a highly crimped drawn yarn wasproduced with a tenacity of about 3.5 grams per denier.

EXAMPLE 4 Three l28-denier yarns of polyethylene terephthalate eachcontaining filaments with a birefringence of 0.008 and an intrinsicviscosity measured in orthochlorophenol at 20 C. of 0.65 were over-endunwound and drawn to a ratio of 3.86 using the drawing process describedin Example 2 but with the hot plate at 215 C. The three yarns wereslotted syrnmetrically into single orbital twister guides as illustratedin FIGS. 2 and 3 of the accompanying drawings placed respectively afterthe hot feed roll and after the hot plate. A dam twist of 25 turns perinch was inserted over the hot plate by rotating the orbitaltwister'guide at 1,100 r.p.m. and the guide was then clamped. The yarnswere plied together after the draw roll to give a drawn crimpedthree-ply torque yarn.

EXAMPLE 5 Three filaments of polyethylene terephthalate extruded at 290C. were separated below the spinneret by a ceramic guide in the form ofa comb before passing them round a heated feed roll at 95 C. and a colddraw roll providing a draw ratio of 3.83 at a final windup speed of8,000 feet per minute at which the filament denier was 15. The threefilaments were symmetrically slotted into two orbital twister guides ofthe type illustrated in FIGS. 2 and 3 of the accompanying drawingsplaced between the feed and draw rolls, and between the guides thefilaments traversed a 2 ft. long grooved hot plate at 230 C. followed bya 1 ft. cooling zone across which a draught of cooling air was provided.The second orbital twister guide was rotated at 1,100 rpm. until a twistof 50 turns per inch had been established in the groove of the hotplate. The guide was then clamped. This integrated spinning, drawing andtextured process provided a three-filament bulked torque yarn.

EXAMPLE 6 Two 80.5 denier spun yarns of polyethylene terephthalate eachcontaining 8 filaments with a birefringence of 0.008 and an intrinsicviscosity of 0.65 determined in a 1 percent solution oforthochlorophenol at 20 C. were drawn separately at a draw ratio of 3.4over a hot feed roll C.) and a hot plate (200 C.) at 2,000 ft./min.finishing with a yarn twist of onehalf turn per inch. The two yarns wereslotted symmetrically into two single orbital twister guides asillustrated in FIGS. 2 and 3 of the accompanying drawings placed betweentwo rolls, both rotating at surface speeds of 400 ft./min., one guidebeing placed between the first roll and a 2 ft. grooved hot plate C.)and the other between a cooling draught of air immediately after the hotplate and the second roll. The two yarns coming from the second rollwere then passed through a 2 ft. hot air tube (air circulating in thesame direction as the yarn at 230 C., 15 psi.) to a third roll rotatingat 200 ft./min.

A darn twist of 60 t.p.i. was inserted on the running threadline overthe hot plate by rotating the orbital twister guide at 1,100 r.p.m. andthe guide was then clamped. The yarns coming from the thlrd rol wereplied giving a stabilized crimped yarn of low torque.

It will be appreciated that although the process and apparatus of thisinvention may be used with any number of strands drawn at any speed atwhich winding means are available, it is particularly useful inconnection with a multiplicity of fine strands drawn at high speeds asencountered in integrated spin draw processes.

What we claim is:

1. A multiple threadline guide, comprising an assembly of individuallythreadable guides symmetrically disposed about an axis of symmetry, suchassembly being rotatable about an axis parallel to such axis of symmetryin bearings having a radius greater than the radius of a circleencompassing all such individual guides, and such assembly beingprovided with means to cause and to prevent such rotation.

2. A multiple threadline guide according to claim 1 in which individualguides are in a plane perpendicular to the axis of rotation and areconcentrically and equally spaced round such axis.

3. A guide according to claim 1 comprising a member in which individualguides formed by inwardly directed slots in a plane at right angles tothe axis of rotation have inner closed ends symmetrically spaced aboutthe axis of rotation within a radius smaller than the radius of suchbearings, and outer open ends which are separately threadable throughslots in the bearings at angular positions of such member in suchbearings at which such slots in the member are inward extensions of suchslots in such bearings.

4. A guide comprising an assembly according to claim 1 rotatably mountedin bearings one part of which may be removed to permit removal,threading and reinsertion of the assembly and then reassembled.

5. A double multiple threadline guide comprising two assemblies ofguides each according to claim 1 rotatable in opposite directions by acommon driving means.

1. A multiple threadline guide, comprising an assembly of individuallythreadable guides symmetrically disposed about an axis of symmetry, suchassembly being rotatable about an axis parallel to such axis of symmetryin bearings having a radius greater than the radius of a circleencompassing all such individual guides, and such assembly beingprovided with means to cause and to prevent such rotation.
 2. A multiplethreadline guide according to claim 1 in which individual guides are ina plane perpendicular to the axis of rotation and are concentrically andequally spaced round such axis.
 3. A guide according to claim 1comprising a member in which individual guides formed by inwardlydirected slots in a plane at right angles to the axis of rotation haveinner closed ends symmetrically spaced about the axis of rotation withina radius smaller than the radius of such bearings, and outer open endswhich are separately threadable through slots in the bearings at angularpositions of such member in such bearings at which such slots in themember are inward extensions of such slots in such bearings.
 4. A guidecomprising an assembly according to claim 1 rotatably mounted inbearings one part of which may be removed to permit removal, threadingand reinsertion of the assembly and then reassembled.
 5. A doublemultiple threadline guide comprising two assemblies of guides eachaccording to claim 1 rotatable in opposite directions by a commondrIving means.